Single-layer capacitive touch unit and capacitive touch screen

ABSTRACT

The invention discloses a single-layer capacitive touch unit, including a sensing electrode, connected to a control unit through a sensing electrode lead; and a plurality of scan electrodes, disposed at two sides of the sensing electrode; the scan electrode being connected to the control unit through a scan electrode lead, and the scan electrodes and the sensing electrode being coplanar; wherein one end of scan electrode lead connected to a second end of scan electrode and extending to near a next scan electrode to form extending lead; and the other end of scan electrode lead connected to the control unit. The invention also provides a capacitive touch screen with the capacitive touch unit. The invention can reduce the effect of noise signal on the touch signal and increase SNR of the touch signal.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of touch techniques, and inparticular to a single-layer capacitive touch unit and a capacitivetouch screen with capacitive touch unit.

2. The Related Arts

The touch display screen as an input medium is one of the simplest andmost convenient modes for human-machine dialogue. Hence, the touchdisplay screen is widely applied to various electronic products. Basedon the operating theory and information transmission medium, the touchscreen products care categorized into four types: infrared touch screen,capacitive touch screen, resistive touch screen and surface acousticwave touch screen, wherein the capacitive touch screen becomes the mainstream technology for touch screen due to the advantages of longlife-span, high transmittance and supporting multi-touch.

The capacitive touch screens include the surface capacitive type and theprojected capacitive type. The projected capacitive type can be dividedinto self-capacitance type and mutual capacitance type. Theself-capacitance type is by using Indium tin oxide (ITO, a transparentconductive material) to form sensing electrode and scan electrode arrayon glass surface. The sensing electrodes and the scanning electrodesrespectively form a capacitance with ground, which is the so-calledself-capacitance, that is, the electrode capacitance to ground. When thefingers touch capacitive screen, the finger capacitance will be added tothe screen capacitance, so that the screen capacitance increases. Indetecting the touch, the self-capacitance screen sequentially detectsthe sensing electrode and the scan electrode array. Based on thecapacitance change before and after the touch, the coordinates of thesensing electrode and the scan electrode are determined respectively andthen combined to become the coordinates of touch point. The scanningmanner of the self-capacitance is equivalent to projecting the touchpoint on the touch screen to the X-axis and Y-axis directions,respectively. Then, the coordinates in the X-axis and Y-axis directionare calculated and combined into the coordinates of the touch point.FIG. 1 shows the theory behind the mutual capacitive touch screen. Themanufacturing of mutual capacitance screen is also to form the sensingelectrode Rx and scan electrodes Tx. The mutual capacitive screendiffers from the self-capacitive screen in that a coupling capacitanceC_(M) is formed where the two groups of electrodes intersect. In otherwords, the two groups of electrodes become the two poles of the couplingcapacitance C_(M). When a finger touches the capacitive screen, thetouch affects the coupling between the two electrodes near the touchpoint, thus changes the value of the coupling capacitance C_(M) betweenthe two electrodes. When detecting the value of mutual capacitance, thesensing electrodes emit excitation signal, and all the scan electrodesreceive the signals. As such, the values of capacitances at all thejunctions of the sensing electrode and the scan electrodes can beobtained, which is the two-dimensional capacitance of the entire touchscreen. According to the information of the change in thetwo-dimensional capacitance of the touch screen, the coordinates of eachtouch point can be calculated. As such, multiple touch points on thescreen can also be calculated.

In the known mutual capacitive touch screen, one approach is tomanufacture the sensing electrodes Rx and scan electrodes Tx with twolayers ITO conductive material respectively, and disposed on twonon-coplanar parallel planes. The touch screen manufactured by thisapproach is called the double layer ITO (DITO) mutual capacitive touchscreen. This approach requires complex manufacturing process and theyield rate is restricted by the manufacturing process. Another approachis to dispose the sensing electrodes Rx and scan electrodes Tx on thesame plane, which is called the single layer ITO (SITO) mutualcapacitive touch screen. Because the sensing electrodes Rx, scanningelectrode array Tx and corresponding connection wires are all disposedon the same plane, how to reduce the effect of noise signal on the touchsignal and improve the touch signal-noise-ratio (SNR) becomes animperative issue.

SUMMARY OF THE INVENTION

To overcome the shortcomings of the known technique, the presentinvention provides a single-layer capacitive touch screen able to reducethe effect of noise signal on the touch signal and improve thesignal-noise-ratio (SNR) of the touch signal.

To achieve the above object, the present invention provides asingle-layer capacitive touch unit, which comprises: a sensingelectrode, connected to a control unit through a sensing electrode lead;and a plurality of scan electrodes, disposed at two sides of the sensingelectrode; the scan electrode being connected to the control unitthrough a scan electrode lead, and the scan electrodes and the sensingelectrode being coplanar; wherein one end of the scan electrode leadbeing connected to a second end of the scan electrode and extending tonear a next scan electrode to form extending lead; and the other end ofthe scan electrode lead being connected to the control unit.

According to a preferred embodiment of the present invention, whereinboth sides of the sensing electrode are further disposed with fillingmetal.

According to a preferred embodiment of the present invention, thefilling metal is a transparent conductive material, and the transparentconductive material is ITO.

According to a preferred embodiment of the present invention, whereinthe sensing electrode comprises a plurality of identical sensingelectrode units, the plurality of sensing electrode units is arrangedregularly along a same direction, the plurality of sensing electrodeunits is electrically connected; each scan electrode comprises aplurality of identical scan electrode units, the plurality of scanelectrode units is arranged regularly along a same direction and thedirection is the same as the sensing electrode units, and the pluralityof scan electrode units is electrically connected.

According to a preferred embodiment of the present invention, a gapbetween two neighboring sensing electrode units is less than 129 um, agap between two neighboring scan electrode units is less than 129 um,and a gap between the neighboring sensing electrode unit and the scanelectrode unit is less than 129 um.

According to a preferred embodiment of the present invention, both thesensing electrode unit and the scan electrode unit are of long stripstructure having a shape of straight line, wave or grid.

According to a preferred embodiment of the present invention, a firstend of the scan electrode is embedded in the sensing electrode, and agap exists between the scan electrode and the sensing electrode.

According to a preferred embodiment of the present invention, the tip ofthe first end of the scan electrode extends laterally along both sides.

According to a preferred embodiment of the present invention, both thesensing electrode unit and the scan electrode unit are made oftransparent conductive material, and the transparent conductive materialis ITO.

According to a preferred embodiment of the present invention, the scanelectrode lead is connected to a second end of the scan electrode, andthen connected to the control unit;

Another object of the present invention is to provide a capacitive touchscreen, which comprises a pixel array substrate, a touch screensubstrate disposed oppositely to the pixel array substrate, and a liquidcrystal layer disposed between the pixel array substrate and the touchscreen substrate; wherein the touch screen substrate further comprisinga touch structure layer, and the touch structure layer comprising aplurality of the aforementioned single-layer capacitive touch units.

Compared to the known techniques, the present invention provides thefollowing advantages:

(1) the present invention extends the end of the scan electrode leadconnected to the scan electrode to near the next electrode to formextending lead for shielding the signal between the scan electrode leadand sensing electrode; the present invention also disposes filling metalbetween the sensing electrode and scan electrode lead to further shieldthe interference of the signal in the scan electrode lead on the sensingelectrode and increase the SNR of touch signal; furthermore, the scanelectrode of the present invention is embedded in the sensing electrodeso that the scan electrode is surrounded by the sensing electrode, whichincreases the capacitance of the mutual capacitance between the twoelectrodes and increases the SNR of the touch signal; and

(2) the present invention divides the sensing electrode and the scanelectrode into a plurality of identical sensing electrode units and scanelectrode units, and the sensing electrode units and scan electrodeunits are coplanar and have the same arrangement direction, so as toachieve the object of reducing the visual perceptibility to human eyeand solve the visual difference between the sensing electrode and scanelectrode array.

BRIEF DESCRIPTION OF THE DRAWINGS

To make the technical solution of the embodiments according to thepresent invention, a brief description of the drawings that arenecessary for the illustration of the embodiments will be given asfollows. Apparently, the drawings described below show only exampleembodiments of the present invention and for those having ordinaryskills in the art, other drawings may be easily obtained from thesedrawings without paying any creative effort. In the drawings:

FIG. 1 is a schematic view showing the theory behind the known mutualcapacitive touch screen;

FIG. 2 is a schematic view showing the structure of a capacitive touchscreen provided by an embodiment of the present invention;

FIG. 3 is a schematic view showing the structure of the touch structurelayer of the capacitive touch screen of FIG. 2;

FIG. 4 is a schematic view showing the structure of the capacitive touchunit provided by an embodiment of the present invention;

FIG. 4A is a schematic view showing another shape of the sensingelectrode unit and the scan electrode unit;

FIG. 4B is a schematic view showing another shape of the sensingelectrode unit and the scan electrode unit; and

FIG. 5 is a schematic view showing the relation between the distance dbetween electrode units and the distance L between the human eye and thetouch interface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As aforementioned, the present invention is to provide a single-layercapacitive touch unit able to reduce the effect of noise signal on thetouch signal and improve the SNR of the touch signal, and a capacitivetouch screen comprising the single-layer capacitive touch unit. Thesingle-layer capacitive touch unit comprises: a sensing electrode,connected to a control unit through a sensing electrode lead; and aplurality of scan electrodes, disposed at two sides of the sensingelectrode; the scan electrode being connected to the control unitthrough a scan electrode lead, and the scan electrodes and the sensingelectrode being coplanar; wherein one end of the scan electrode leadbeing connected to a second end of the scan electrode and extending tonear a next scan electrode to form extending lead; and the other end ofthe scan electrode lead being connected to the control unit.

In the aforementioned capacitive touch unit, the end of the scanelectrode lead connected to the scan electrode to near the nextelectrode to form extending lead for shielding the signal between thescan electrode lead and sensing electrode, so as to reduce theinterference of the signal in the scan electrode lead on the sensingelectrode and increase the SNR of touch signal.

The following describes the invention in details with drawings andembodiments.

As shown in FIG. 2, the capacitive touch screen of the presentembodiment comprises a pixel array substrate 3, a touch screen substrate1 disposed oppositely to the pixel array substrate 3, and a liquidcrystal layer 2 disposed between the pixel array substrate 3 and thetouch screen substrate 1; wherein the touch screen substrate furthercomprising a touch structure layer 1 a, and the touch structure layer 1a comprising a plurality of the aforementioned capacitive touch units 10(as shown in FIG. 3).

In the instant embodiment, the single-layer capacitive touch unit 10comprises the following structure, as shown in FIG. 4: a sensingelectrode 200, connected to a control unit through a sensing electrodelead 2003; and a plurality of scan electrodes, such as scan electrode300, 301, 302 and 303, disposed at two sides of the sensing electrode200. Each of the scan electrodes 300-303 are connected to the controlunit through a scan electrode lead 3003, and the scan electrodes 300-303and the sensing electrode 200 are coplanar.

In the instant embodiment, the end of the scan electrode lead 3003connected to the second end 300 b of the scan electrode 300 and extendsto near the next scan electrode 302 to form extending lead 3003 a. Theother end of the scan electrode lead 3003 is connected to the controlunit.

In the instant embodiment, both the sensing electrode units 2001 and thescan electrode unit 3001 are made of transparent conductive material.The transparent conductive material is ITO.

In the instant embodiment, both sides of the sensing electrode 200 arefurther disposed with filling metal 100, for filling up the gap areabetween the sensing electrode 200 and the scan electrode lead 3003 aswell as acting as shielding protective layer for the sensing electrode200. The filling metal 100 is a transparent conductive material, and thetransparent conductive material is ITO.

In the instant embodiment, a first end 300 a of the scan electrode 300is embedded in the sensing electrode 200. A gap exists between the scanelectrode 300 and the sensing electrode 200. Furthermore, the tip of thefirst end 300 a of the scan electrode 300 extends laterally along bothsides.

In the aforementioned single-layer capacitive touch unit, the end of thescan electrode lead connected to the scan electrode is extended to nearthe next electrode to form extending lead for shielding the signalbetween the scan electrode lead and sensing electrode during the scanelectrode receiving signals sequentially. The present invention alsodisposes filling metal between the sensing electrode and scan electrodelead to further shield the interference of the signal in the scanelectrode lead on the sensing electrode and increase the SNR of touchsignal. Furthermore, the scan electrode of the present invention isembedded in the sensing electrode so that the scan electrode issurrounded by the sensing electrode, which increases the capacitance ofthe mutual capacitance between the two electrodes and increases the SNRof the touch signal.

In the instant embodiment, the sensing electrode 200 comprises aplurality of identical sensing electrode units 2001, the plurality ofsensing electrode units 2001 is arranged regularly along a samedirection, and the plurality of sensing electrode units 2001 iselectrically connected. Each scan electrode 300 comprises a plurality ofidentical scan electrode units 3001, the plurality of scan electrodeunits 3001 is arranged regularly along a same direction and thedirection is the same as the sensing electrode units 2001, and theplurality of scan electrode units 3001 is electrically connected througha second lead 3002. In addition, both the sensing electrode unit 2001and the scan electrode unit 3001 are of long strip structure having astraight line shape. In other embodiments, both the sensing electrodeunit 2001 and the scan electrode unit 3001 may be of long stripstructure having other shapes, such as, wave or grid shown in FIG. 4Aand FIG. 4B, respectively.

In the instant embodiment, a gap between two neighboring sensingelectrode units 2001 is less than 129 um, a gap between two neighboringscan electrode units 3001 is less than 129 um, and a gap between theneighboring sensing electrode unit 2001 and the scan electrode unit 3001is less than 129 um.

In the instant embodiment, the filling metal 100 comprises a pluralityof filling metal units of long strip structure having a straight lineshape. The distances between two neighboring filling metal units,between neighboring sensing electrode unit 2001 and the filling metalunits, and between the neighboring scan electrode unit 3001 and thefilling metal units are all less than 129 um.

Regarding the choice on the distance between the electrode units, it isnecessary to take the human eye resolution limit and the viewingdistance into account. The displaying technique considers that the humaneye resolution limit has an angle of 1′, but the known retina availablein the market shows that the human eye resolution limit has an angle of0.59′, which means that the display needs to provide higher resolution.As shown in FIG. 5, L is the distance between the human eye and thetouch interface, θ is the human eye resolution limit angle, d is thedistance of neighboring electrode units, wherein the d≈L×θ. In theinstant embodiment, the distance between human eye and the touchinterface is 75 cm (based on the average arm length of a grown up),θ=0.59′=0.000172 arc, then:d≈L×θ=75 cm×10000×0.000172=129 μm

It should be noted that the choice of d=129 um is only for illustrative.In other embodiments, the distance between human eye and the touchinterface can be estimated based on the application object of the touchscreen so as to select a different distance d between electrode units.

As in the aforementioned capacitive touch unit, the sensing electrode200 and the scan electrode 300 are respectively divided into a pluralityof sensing electrode units 2001 and scan electrode units 3001, which areof long strip structure having a straight line shape. The sensingelectrode units 2001 and the scan electrode units 3001 are coplanar andhave the same arrangement direction. Also, through controlling thedistance d between electrode units, the object to reduce the perceptibledifference to human eye and solve the visual difference between thesensing electrode and scan electrode array is achieved.

In summary, the present invention extends the end of the scan electrodelead connected to the scan electrode to near the next electrode to formextending lead for shielding the signal between the scan electrode leadand sensing electrode; the present invention also disposes filling metalbetween the sensing electrode and scan electrode lead to further shieldthe interference of the signal in the scan electrode lead on the sensingelectrode and increase the SNR of touch signal; furthermore, the scanelectrode of the present invention is embedded in the sensing electrodeso that the scan electrode is surrounded by the sensing electrode, whichincreases the capacitance of the mutual capacitance between the twoelectrodes and increases the SNR of the touch signal. Also, the presentinvention divides the sensing electrode and the scan electrode into aplurality of identical sensing electrode units and scan electrode units,and the sensing electrode units and scan electrode units are coplanarand have the same arrangement direction, so as to achieve the object ofreducing the visual perceptibility to human eye and solve the visualdifference between the sensing electrode and scan electrode array.

It should be noted that in the present disclosure the terms, such as,first, second are only for distinguishing an entity or operation fromanother entity or operation, and does not imply any specific relation ororder between the entities or operations. Also, the terms “comprises”,“include”, and other similar variations, do not exclude the inclusion ofother non-listed elements. Without further restrictions, the expression“comprises a . . . ” does not exclude other identical elements frompresence besides the listed elements.

Embodiments of the present invention have been described, but notintending to impose any unduly constraint to the appended claims. Anymodification of equivalent structure or equivalent process madeaccording to the disclosure and drawings of the present invention, orany application thereof, directly or indirectly, to other related fieldsof technique, is considered encompassed in the scope of protectiondefined by the clams of the present invention.

What is claimed is:
 1. A single-layer capacitive touch unit, whichcomprises: a sensing electrode, connected to a control unit through asensing electrode lead; and a plurality of scan electrodes, disposed attwo sides of the sensing electrode; each of the scan electrodes beingconnected to the control unit through a scan electrode lead, and thescan electrodes and the sensing electrode being coplanar; wherein oneend of a selected one of the scan electrode leads is connected to asecond end of a selected one of the scan electrodes and extends to neara next scan electrode, which is one of the scan electrodes other thanthe selected scan electrode, to form an extending lead; and the otherend of the selected scan electrode lead is connected to the controlunit.
 2. The single-layer capacitive touch unit as claimed in claim 1,wherein both sides of the sensing electrode are further disposed withfilling metal.
 3. The single-layer capacitive touch unit as claimed inclaim 2, wherein the sensing electrode comprises a plurality ofidentical sensing electrode units, the plurality of sensing electrodeunits is arranged regularly along a same direction, the plurality ofsensing electrode units is electrically connected; each scan electrodecomprises a plurality of identical scan electrode units, the pluralityof scan electrode units is arranged regularly along a same direction andthe direction is the same as the sensing electrode units, and theplurality of scan electrode units is electrically connected.
 4. Thesingle-layer capacitive touch unit as claimed in claim 3, wherein a gapbetween two neighboring sensing electrode units is less than 129 um , agap between two neighboring scan electrode units is less than 129 um,and a gap between the neighboring sensing electrode unit and the scanelectrode unit is less than 129 um.
 5. The single-layer capacitive touchunit as claimed in claim 3, wherein the sensing electrode units and thescan electrode units are of long strip structure having a shape ofstraight line, wave or grid.
 6. The single-layer capacitive touch unitas claimed in claim 3, wherein the sensing electrode units and the scanelectrode units are made of transparent conductive material; and thetransparent conductive material is ITO.
 7. The single-layer capacitivetouch unit as claimed in claim 2, wherein the filling metal is atransparent conductive material, and the transparent conductive materialis ITO.
 8. The single-layer capacitive touch unit as claimed in claim 1,wherein a first end of the selected scan electrode is embedded in thesensing electrode, and a gap exists between the selected scan electrodeand the sensing electrode.
 9. The single-layer capacitive touch unit asclaimed in claim 8, wherein the tip of the first end of the selectedscan electrode extends laterally along the direction in which theextending lead extends.
 10. The single-layer capacitive touch unit asclaimed in claim 1, wherein the sensing electrode and the scanelectrodes are made of transparent conductive material; and thetransparent conductive material is ITO.
 11. A capacitive touch screen,which comprises: a pixel array substrate, a touch screen substratedisposed oppositely to the pixel array substrate, and a liquid crystallayer disposed between the pixel array substrate and the touch screensubstrate; wherein the touch screen substrate further comprising a touchstructure layer, and the touch structure layer comprising a plurality ofcapacitive touch units; the capacitive touch unit further comprising: asensing electrode, connected to a control unit through a sensingelectrode lead; and a plurality of scan electrodes, disposed at twosides of the sensing electrode; each of the scan electrodes beingconnected to the control unit through a scan electrode lead, and thescan electrodes and the sensing electrode being coplanar; wherein oneend of a selected one of the scan electrode leads is connected to asecond end of a selected one of the scan electrodes and extends to neara next scan electrode, which is one of the scan electrodes other thanthe selected scan electrode, to form an extending lead; and the otherend of the selected scan electrode lead is connected to the controlunit.
 12. The capacitive touch screen as claimed in claim 11, whereinboth sides of the sensing electrode are further disposed with fillingmetal.
 13. The capacitive touch screen as claimed in claim 12, whereinthe filling metal is a transparent conductive material, and thetransparent conductive material is ITO.
 14. The capacitive touch screenas claimed in claim 12, wherein the sensing electrode comprises aplurality of identical sensing electrode units, the plurality of sensingelectrode units is arranged regularly along a same direction, theplurality of sensing electrode units is electrically connected; eachscan electrode comprises a plurality of identical scan electrode units,the plurality of scan electrode units is arranged regularly along a samedirection and the direction is the same as the sensing electrode units,and the plurality of scan electrode units is electrically connected. 15.The capacitive touch screen as claimed in claim 14, wherein a gapbetween two neighboring sensing electrode units is less than 129 um, agap between two neighboring scan electrode units is less than 129 um,and a gap between the neighboring sensing electrode unit and the scanelectrode unit is less than 129 um.
 16. The capacitive touch screen asclaimed in claim 14, wherein the sensing electrode units and the scanelectrode units are of long strip structure having a shape of straightline, wave or grid.
 17. The capacitive touch screen as claimed in claim14, wherein the sensing electrode units and the scan electrode units aremade of transparent conductive material; and the transparent conductivematerial is ITO.
 18. The capacitive touch screen as claimed in claim 11,wherein a first end of the selected scan electrode is embedded in thesensing electrode, and a gap exists between the selected scan electrodeand the sensing electrode.
 19. The capacitive touch screen as claimed inclaim 18, wherein the tip of the first end of the selected scanelectrode extends laterally along the direction in which the extendinglead extends.
 20. The capacitive touch screen as claimed in claim 11,wherein the sensing electrode and the scan electrodes are made oftransparent conductive material; and the transparent conductive materialis ITO.